Custom Formula Field Questions

Custom Formula Field Questions

I'd like to have a custom field that looks at another customer field with a pick list and selects the appropriate price.  I have created multiple formula fields with a fixed integer for the pricing fields.

Here is the formula I have written:

If(${Potentials.Version of t4 Underground}="Premium", ${Potentials.Premium Price}, If(${Potentials.Version of t4 Underground}="Standard", ${Potentials.Standard Price}, If(${Potentials.Version of t4 Underground}="Basic", ${Potentials.Basic Price}, ${Potentials.Contractor Price})))


I get an error that says "Double quotes not allowed in this expression. Only single quotes"  I replaced all of the double quotes with single quotes and got another error that said quotes were missing.

What is the correct syntax to get an if statement to be based on the value of a picklist field?